Suplementação de Novilhos Mestiços durante a Época das Águas: Parâmetros Ingestivos e Digestivos

Abstract

The effects of supplementation of crossbred steers on pasture during the wet season on dry matter (DMI), forage (FI), neutral detergent fiber (NDFI) and crude protein (CPI) intakes; digestibility of DM (DMD), NDF (NDFD) and CP (CPD); rate of passage of ruminal particles (RPR) and total mean retention time (TMRT) of the digesta; pH and concentrations of amoniacal-N in the rumen, were evaluated. Five F1 Limousin x Nelore steers fistulated in the rumen and esophagus and supplemented on Brachiaria decumbens pasture were used. The experiment was carried out in three experimental periods, according to a randomized blocks design, being the periods considered blocks. The supplements were: mineral salt (SAL); supplements based on corn and soybean meal, with 20% CP, at the level of 1.0 and 2.0 kg/day (MS1 and MS2); and supplements based on wheat bran and soybean meal, with 20% CP, at the level of 1.0 and 2.0 kg/day (TS1 and TS2), daily fed at 10 a.m. The supplementation decreased DMI, FI, and NDFI, being more prominent for the supplements based on corn, although without significant effects. RPR, TMRT and ruminal pH did not differ among treatments. There was interaction supplement x time of collection on concentration of amoniacal-N, without elevating the basal levels; the treatments SAL and MSI did not differ and did not vary with the time. The treatments MS2 and TS1 did not differ at any time, presenting quadratic profiles, similar to TS2, which demonstrated the largest concentrations of amoniacal-N in the times other than zero.